My simulation is 2D and consists of a thin walled envelope with pressure applied to the internal walls. At the bottom left a semicircle is fixed in space. Outside of the envelope there is no other force. I added a long straight member just for visualization. The funny thing is, this long straight member appears to become longer in the simulation results. Not only this, but the rest of the part seems to grow or swell in the material's thickness. The results show zero stress or strain in the long straight member, which is correct. The displacement values calculated are way too larger to be physically possible (The max. displacement in the results is much longer than if the part was fully stretched straight). Has anyone seen something like this before?

There is an option to multiply displacement or to use actual. Right-click on Stress/Deflection, etc. and choose (I think) it is Definition - first tab in any case - you would normally see the results automatically scaled. You can set it to non-deformed, actual, or some scale you'd like to see. I could post a pic when my current job is done solving.

Thanks for the response, but the problem does not deal with the deformation scale in the results options. In the images that I posted, you can see all of the loads (pressure) applied to a closed volume. There is no force or restraint that would effect the long straight section of this model, yet that section appears to elongate. Also, the values calculated for displacement indicate that the part must elongate very significantly (well beyond what would be realistic). At the same time, the stress and strain calculated in the straight section is zero, which is correct.

The problem was my choice of linear solver. For the large displacement that I may expect, using the nonlinear solver appears to output much more realistic results. I found a similar situation in this video: